From 61e28cf0543c7d8e6ef88c3c305f727c5a21ba5b Mon Sep 17 00:00:00 2001 From: Joao Martins Date: Sat, 29 Jan 2022 13:41:01 -0800 Subject: [PATCH] memory-failure: fetch compound_head after pgmap_pfn_valid() memory_failure_dev_pagemap() at the moment assumes base pages (e.g. dax_lock_page()). For devmap with compound pages fetch the compound_head in case a tail page memory failure is being handled. Currently this is a nop, but in the advent of compound pages in dev_pagemap it allows memory_failure_dev_pagemap() to keep working. Without this fix memory-failure handling (i.e. MCEs on pmem) with device-dax configured namespaces will regress (and crash). Link: https://lkml.kernel.org/r/20211202204422.26777-2-joao.m.martins@oracle.com Reported-by: Jane Chu Signed-off-by: Joao Martins Reviewed-by: Naoya Horiguchi Reviewed-by: Dan Williams Reviewed-by: Muchun Song Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory-failure.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 14ae5c1..97a9ed8 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1596,6 +1596,12 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags, } /* + * Pages instantiated by device-dax (not filesystem-dax) + * may be compound pages. + */ + page = compound_head(page); + + /* * Prevent the inode from being freed while we are interrogating * the address_space, typically this would be handled by * lock_page(), but dax pages do not use the page lock. This -- 2.7.4